The present invention relates to a monoclonal antibody capable of specifically reacting with the human mesothelial cell and to a method of producing the monoclonal antibody. The present invention is useful in diagnosis of cancers such as cytological diagnosis of expectoration for lung cancer, cytological diagnosis of pleural effusion for lung cancer and cytological diagnosis of ascitic fluid for various abdominal cancers.
It is known that in lung cancer, cancer cells desquamate into sputum and/or pleural effusion, and that in various abdominal cancers, cancer cells desquamate into ascitic fluid. Therefore, it is important in diagnosis of cancer to detect cancer cells desquamating into sputum and/or pleural effusion, or ascitic fluid. Diagnosis and differentiation of cancer cells are generally carried out by pathologists. Sputum, pleural effusion and ascitic fluid contain many kinds of normal cells, and above all it is difficult to distinguish cancer cells from mesothelial cells and macrophages.
Recently, many monoclonal antibodies having specificity for cancer cells have been produced by hybridoma technique, and application of the monoclonal antibodies to cytodiagnosis have been made. Since some of the monoclonal antibodies react with macrophages and/or mesothelial cells or some of them react only with particular cancer cells, it is not easy to carry out cytodiagnosis of cancer by use of the monoclonal antibodies. Especially, it is difficult for even a pathologist to distinguish cancer cells from mesothelial cells.
Accordingly, a monoclonal antibody which specifically reacts with the mesothelial cell but not with cancer cells, if available, would be useful in the cytodiagnosis of cancer. No monoclonal antibodies and antisera being capable of specifically reacting with the mesothelial cell have been know so far.
The present inventors have first produced hybridomas between spleen cells of a mouse immunized with human mesothelial cells and murine myeloma cells and selected a hybridoma producing a monoclonal antibody which is capable of specifically reacting with human mesothelial cells but not with various human cancer cells. Further, the present inventors have made cytological diagnosis of expectoration, pleural effusion and ascitic fluid from patients with cancer using the monoclonal antibody of the present invention has a great significance in clinical pathology, and have now completed the present invention.